Treatment of hypersensitivity conditions

ABSTRACT

This invention relates to methods of treatment of hypersensitivity conditions such as asthma and other allergic conditions, and especially to treatment of these conditions with cyclic peptidic and peptidomimetic compounds which have the ability to modulate the activity of G protein-coupled receptors. The compounds preferably act as antagonists of the C 5   a  receptor, and are active against C 5   a  receptors on polymorphonuclear leukocytes and macrophages. Particularly preferred compounds for use in the methods of the invention are disclosed.

FIELD OF THE INVENTION

This invention relates to the treatment of hypersensitivity conditionssuch as asthma and other allergic conditions, and especially totreatment of these conditions with novel cyclic peptidic andpeptidomimetic compounds which have the ability to modulate the activityof G protein-coupled receptors. The compounds preferably act asantagonists of the C5a receptor, and are active against C5a receptors onpolymorphonuclear leukocytes and macrophages.

BACKGROUND OF THE INVENTION

All references, including any patents or patent applications, cited inthis specification are hereby incorporated by reference. No admission ismade that any reference constitutes prior art. The discussion of thereferences states what their authors assert, and the applicants reservethe right to challenge the accuracy and pertinency of the citeddocuments. It will be clearly understood that, although a number ofprior art publications are referred to herein, this reference does notconstitute an admission that any of these documents forms part of thecommon general knowledge in the art, in Australia or in any othercountry.

G protein-coupled receptors are prevalent throughout the human body,comprising approximately 60% of known cellular receptor types, andmediate signal transduction across the cell membrane for a very widerange of endogenous ligands. They participate in a diverse array ofphysiological and pathophysiological processes, including, but notlimited to those associated with cardiovascular, central and peripheralnervous system, reproductive, metabolic, digestive, immunological,inflammatory, and growth disorders, as well as other cell-regulatory andproliferative disorders. Agents which selectively modulate functions ofG protein-coupled receptors have important therapeutic applications.These receptors are becoming increasingly recognised as important drugtargets, due to their crucial roles in signal transduction (Gprotein-coupled Receptors, IBC Biomedical Library Series, 1996).

One of the most intensively studied G protein-coupled receptors is thereceptor for C5a. C5a is one of the most potent chemotactic agentsknown, and recruits neutrophils and macrophages to sites of injury;alters their morphology; induces degranulation; increases calciummobilisation, vascular permeability (oedema) and neutrophiladhesiveness; contracts smooth muscle; stimulates release ofinflammatory mediators, including histamine, TNF-α, IL-1, IL-6, IL-8,prostaglandins, and leukotrienes, and of lysosomal enzymes; promotesformation of oxygen radicals; and enhances antibody production (Gerardand Gerard, 1994).

Agents which limit the pro-inflammatory actions of C5a have potentialfor inhibiting chronic inflammation, and its accompanying pain andtissue damage. For these reasons, molecules which prevent C5a frombinding to its receptors are useful for treating chronic inflammatorydisorders driven by complement activation. Such compounds also providevaluable new insights into the mechanisms of complement-mediatedimmunity.

In our previous application No. PCT/AU98/00490 we described thethree-dimensional structure of some analogues of the C-terminus of humanC5a, and used this information to design novel compounds which bind tothe human C5a receptor (C5aR), behaving as either agonists orantagonists of C5a. It had previously been thought that a putativeantagonist might require both a C-terminal arginine and a C-terminalcarboxylate for receptor binding and antagonist activity (Konteatis etal, 1994). We showed that in fact a terminal carboxylate group is notgenerally required either for high affinity binding to

C5aR or for antagonist activity. Instead we found that a hithertounrecognised structural feature, a turn conformation, was the keyrecognition feature for high affinity binding to the human C5a receptoron neutrophils. As described in our international patent application No.PCT/AU02/01427, filed on 17^(th) Oct. 2002, we used further refinementsof these findings to design more tightly constrained structuraltemplates which enable hydrophobic groups to be assembled into ahydrophobic array for interaction with a C5a receptor. We havesubsequently found that a preferred compound of this class is able toinhibit cardiac and pulmonary fibrosis, and this is described in ourinternational patent application No. PCT/AU03/00415, filed on 7^(th)Apr. 2003. The entire disclosures of these specifications areincorporated herein by this reference.

Asthma is a potentially life-threatening condition characterized byparoxysmal attacks of bronchospasm, which cause wheezing, tightness inthe chest, and difficulty in breathing. Asthmatic attacks may beprovoked by exposure to a variety of stimuli, such as allergens,infection, exercise, changes in ambient temperature or humidity,cigarette smoke, stress or emotional upset. Although attacks can occurat any stage of life, asthma usually has its onset during childhood; itmay be associated with other hypersensitivity conditions such as eczemaor hay fever. Asthma affects up to 16 million Americans, includingapproximately 10-12% of children under age 18, and its incidence isincreasing. It is more common in individuals under the age of 40, and isthe leading cause of absence from school and admission to hospital amongchildren. People who have a family history of asthma or who haveallergies have an increased risk of developing the disease.

Treatment is predominantly with bronchodilators such as β₂-adrenergicagonists, administered orally or as inhaled aerosols, andcorticosteroids are used in severe cases. Metered-dose inhalers, drypowder inhalers and nebulizers are widely used for inhalation therapy.However, despite intensive research the available therapies are unableto control symptoms in all patients. Asthma is associated with verysignificant morbidity, is responsible for a high proportion of hospitalemergency room admissions, and causes a number of deaths each year. Inaddition to this, the economic cost of asthma is very high.

Eczema or eczematous dermatitis is an inflammatory dermatitis associatedwith itching and vesicle formation, followed by weeping and crusting ofthe lesions. In the more chronic forms there may be lichenificationand/or thickening, excoriation, or pigmentation changes; these can bedisfiguring. The allergic or atopic form of eczema can be caused by avariety of allergens, which may be inhaled, contact or food allergens;it can be very difficult to identify the allergen responsible. Atopiceczema is common in childhood. Topical steroids are the primaryfirst-line treatment. Hand dermatitis is a form of atopic dermatitis,which affects an estimated 1.9 million people in the United States.Chronic hand dermatitis will repeatedly relapse or flare. It can involve25-90% of the hands and affect one or both surfaces. Treatment isusually with topical corticosteroids, but this may have limited success,and is associated with side effects such as skin atrophy. Targretin, avitamin A analogue, has recently been approved in the United States fortreatment of hand dermatitis.

Dermatitis is also a major veterinary problem, and is common in domesticanimals such as horses, and in companion animals such as cats and dogs.For example, approximately 5% to 10% of the current U.S. dog population,or four to seven million dogs, is affected. Due to the chronic nature ofallergic dermatitis in affected dogs, the estimated number of treatmentsper year is in excess of 8 million. Current treatment primarily usesmedicated shampoos and conditioners with severe cases requiringtreatment with glucocorticoids.

A variety of agents, including immunoglobulin E (IgE)-targetingmonoclonal antibodies, tumour necrosis factor antagonists,immunosuppressive agent such as tacrolimus and pimecrolimus, andphototherapies, are in various stages of clinical trial for thetreatment of hypersensitivity conditions.

However, there is a great need in the art for effective, non-toxicagents for the treatment of asthma and other hypersensitivityconditions, which do not require administration by injection, and whichcan be produced at reasonable cost. To our knowledge none of theseapproved or experimental agents, and in particular no small moleculeagent, targets the C5a receptor.

SUMMARY OF THE INVENTION

We now show for the first time that a specific inhibitor of the C5areceptor is able to ameliorate asthma in a mammal. This is the firstreported case of an inhibitor of the complement system being used tomodulate pathology in asthma.

According to a first aspect, the invention provides a method oftreatment of a hypersensitivity conditions, comprising the step ofadministering an effective amount of an inhibitor of a G protein-coupledreceptor to a subject in need of such treatment.

Preferably the inhibitor is a compound which

-   (a) is an antagonist of a G protein-coupled receptor,-   (b) has substantially no agonist activity, and-   (c) is a cyclic peptide or peptidomimetic compound of formula I

where A is H, alkyl, aryl, NH₂, NH-alkyl, N(alkyl)₂, NH-aryl, NH-acyl,NH-benzoyl, NHSO₃, NHSO₂-alkyl, NHSO₂-aryl, OH, O-alkyl, or O-aryl;

B is an alkyl, aryl, phenyl, benzyl, naphthyl or indole group, or theside chain of a D- or L-amino acid such as L-phenylalanine orL-phenylglycine, but is not the side chain of glycine, D-phenylalanine,L-homophenylalanine, L-tryptophan, L-homotryptophan, L-tyrosine, orL-homotyrosine;

C is a small substituent, such as the side chain of a D-, L- orhomo-amino acid such as glycine, alanine, leucine, valine, proline,hydroxyproline, or thioproline, but is preferably not a bulkysubstituent such as isoleucine, phenylalanine, or cyclohexylalanine;

D is the side chain of a neutral D-amino acid such as D-Leucine,D-homoleucine, D-cyclohexylalanine, D-homocyclohexylalanine, D-valine,D-norleucine, D-homo-norleucine, D-phenylalanine,D-tetrahydroisoquinoline, D-glutamine, D-glutamate, or D-tyrosine, butis preferably not a small substituent such as the side chain of glycineor D-alanine, a bulky planar side chain such as D-tryptophan, or a bulkycharged side chain such as D-arginine or D-Lysine;

E is a bulky substituent, such as the side chain of an amino acidselected from the group consisting of L-phenylalanine, L-tryptophan andL-homotryptophan, or is L-1-napthyl or L-3-benzothienyl alanine, but isnot the side chain of D-tryptophan, L-N-methyltryptophan,L-homophenylalanine, L-2-naphthyl L-tetrahydroisoquinoline,L-cyclohexylalanine, D-leucine, L-fluorenylalanine, or L-histidine;

F is the side chain of L-arginine, L-homoarginine, L-citrulline, orL-canavanine, or a bioisostere thereof, ie. a side chain in which theterminal guanidine or urea group is retained, but the carbon backbone isreplaced by a group which has different structure but is such that theside chain as a whole reacts with the target protein in the same way asthe parent group; and

X is —(CH₂)_(n)NH— or (CH₂)_(n)—S—, where n is an integer of from 1 to4, preferably 2 or 3; —(CH₂)₂O—; —(CH₂)₃O—; —(CH₂)₃—; —(CH₂)₄—;—CH₂COCHRNH—; or —CH₂—CHCOCHRNH—, where R is the side chain of anycommon or uncommon amino acid.

In C, both the cis and trans forms of hydroxyproline and thioproline maybe used.

Preferably A is an acetamide group, an aminomethyl group, or asubstituted or unsubstituted sulphonamide group.

Preferably where A is a substituted sulphonamide, the substituent is analkyl chain of 1 to 6, preferably 1 to 4 carbon atoms, or a phenyl ortoluyl group.

In a particularly preferred embodiment, the compound has antagonistactivity against C5aR, and has no C5a agonist activity.

The compound is preferably an antagonist of C5a receptors on human andmammalian cells including, but not limited to, human polymorphonuclearleukocytes and human macrophages. The compound preferably binds potentlyand selectively to C5a receptors, and more preferably has potentantagonist activity at sub-micromolar concentrations. Even morepreferably the compound has a receptor affinity IC50<25 μM, and anantagonist potency IC50<1 μm.

Most preferably the compound is selected from the group consisting ofcompounds 1 to 6, 10 to 15, 17, 19, 20, 22, 25, 26, 28, 30, 31, 33 to37, 39 to 45, 47 to 50, 52 to 58 and 60 to 70 described in provisionalapplication No. PCT/AU02/01427. In a particularly preferred embodiment,the compound is PMX53 (compound 1), compound 33, compound 60 or compound45 described therein.

In a second aspect the invention provides the use of a compound asdefined above in the manufacture of a medicament for the treatment of ahypersensitivity condition.

The hypersensitivity condition may be any state in whichcomplement-mediated tissue damage results from the immune reaction of asensitised or immunized individual to a subsequent exposure to antigen.These include but are not limited to Type II immediate hypersensitivity(cytotoxic) and Type III (complex-mediated) immediate hypersensitivity,such as asthma, eczema or dermatitis, and Arthus-type reactions such asserum sickness, glomerulonephritis, hypereosinophilia syndrome, andfarmer's lung. In one preferred embodiment the hypersensitivitycondition is asthma, eczema or dermatitis.

The inhibitor may be used in conjunction with one or more other agentsfor the treatment of hypersensitivity conditions. For asthma, theseinclude but are not limited to bronchodilators such as β₂-adrenergicagonists, including but not limited to albuterol (Ventolin),anti-histamines such as chlorpheniramine, diphenhydramine, ormepyramine, mast cell stabilisers like nedocromil, leukotriene blockerslike zileutin, montelukast and zaphirlukast, muscarinic antagonists likeipratropium and corticosteroids such as prednisolone, budesonide andfluticasone and synthetic steroids or analogues thereof. For eczemathese include but are not limited to topical corticosteroids andsynthetic steroids or analogues thereof, and Vitamin A analogues such asbexarotene (“Targretin”). The inhibitor may alternatively oradditionally be used in conjunction with antiinflammatories, such aseicosapentanoic acid derivatives and omega-3 oils.

The compounds of the invention may be formulated for oral, parenteral,inhalational, intranasal, topical or transdermal use. Suitableformulations for administration by any desired route may be prepared bystandard methods, for example by reference to well-known textbooks suchas Remington: The Science and Practice of Pharmacy, Vol. II, 2000(20^(th) edition), A. R. Gennaro (ed), Williams & Wilkins, Pa.

While the invention is not in any way restricted to the treatment of anyparticular animal or species, it is particularly contemplated that themethod of the invention will be useful in medical treatment of humans,and will also be useful in veterinary treatment, particularly ofcompanion animals such as cats and dogs, livestock such as cattle,horses and sheep, and zoo animals, including non-human primates, largebovids, felids, ungulates and canids.

The compound may be administered at any suitable dose and by anysuitable route. Oral, topical or intranasal administration is preferred,because of the greater convenience and acceptability of these routes.Oral formulations are particularly preferred. It is expected that mostif not all compounds of the invention will be stable in the presence ofmetabolic enzymes, such as those of the gut, blood, lung orintracellular enzymes. Such stability can readily be tested by routinemethods known to those skilled in the art.

The effective dose will depend on the nature of the condition to betreated, and the age, weight, and underlying state of health of theindividual treatment. This will be at the discretion of the attendingphysician or veterinarian. Suitable dosage levels may readily bedetermined by trial and error experimentation, using methods which arewell known in the art.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the inhibition of the vascular leakage associated with adermal Arthus reaction by intravenous (A), oral (B) and topical (C)AcF-[OPdChaWR], and appropriate controls (D).

FIG. 2 shows the inhibition of the rise in circulating TNFα associatedwith a dermal Arthus reaction by intravenous (A), oral (B) and topical(C) AcF-[OPdChaWR], and appropriate topical controls (D).

FIG. 3 shows the reduction of the pathology index associated with adermal Arthus reaction by intravenous, oral and topical AcF-[OPdChaWR].

FIG. 4 illustrates the response of a dog with allergic dermatitisassociated with flea infestation accompanied by demodectic mange totreatment with PMX53.

DETAILED DESCRIPTION OF THE INVENTION

It is to be clearly understood that this invention is not limited to theparticular materials and methods described herein, as these may vary. Itis also to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and it is notintended to limit the scope of the present invention, which will belimited only by the appended claims.

In the claims which follow and in the preceding description of theinvention, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theinvention.

As used herein, the singular forms “a”, “an”, and “the” include pluralreference unless the context clearly dictates otherwise. Thus, forexample, a reference to “an enzyme” includes a plurality of suchenzymes, and a reference to “an amino acid” is a reference to one ormore amino acids. Unless defined otherwise, all technical and scientificterms used herein have the same meaning as commonly understood by one ofordinary skill in the art to which this invention belongs. Although anymaterials and methods similar or equivalent to those described hereincan be used to practice or test the present invention, the preferredmaterials and methods are now described.

Abbreviations used herein are as follows:

-   D-Cha D-cyclohexylamine-   LPS lipopolysaccharide-   PMN polymorphonuclear granulocyte-   RMSD root mean square deviation-   rp-HPLC reverse phase-high performance liquid chromatography-   TFA trifluoroacetic acid;

Throughout the specification conventional single-letter and three-lettercodes are used to represent amino acids.

For the purposes of this specification, the term “alkyl” is to be takento mean a straight, branched, or cyclic, substituted or unsubstitutedalkyl chain of 1 to 6, preferably 1 to 4 carbons. Most preferably thealkyl group is a methyl group. The term “acyl” is to be taken to mean asubstituted or unsubstituted acyl of 1 to 6, preferably 1 to 4 carbonatoms. Most preferably the acyl group is acetyl. The term “aryl” is tobe understood to mean a substituted or unsubstituted homocyclic orheterocyclic aryl group, in which the ring preferably has 5 or 6members.

A “common” amino acid is a L-amino acid selected from the groupconsisting of glycine, leucine, isoleucine, valine, alanine,phenylalanine, tyrosine, tryptophan, aspartate, asparagine, glutamate,glutamine, cysteine, methionine, arginine, lysine, proline, serine,threonine and histidine.

An “uncommon” amino acid includes, but is not restricted to, D-aminoacids, homo-amino acids, N-alkyl amino acids, dehydroamino acids,aromatic amino acids other than phenylalanine, tyrosine and tryptophan,ortho-, meta- or para-aminobenzoic acid, ornithine, citrulline,canavanine, norleucine, γ-glutamic acid, aminobutyric acid,L-fluorenylalanine, L-3-benzothienylalanine, and α,α-disubstituted aminoacids.

Generally, the terms “treating”, “treatment” and the like are usedherein to mean affecting a subject, tissue or cell to obtain a desiredpharmacological and/or physiological effect. The effect may beprophylactic in terms of completely or partially preventing a disease orsign or symptom thereof, and/or may be therapeutic in terms of a partialor complete cure of a disease.

“Treating” as used herein covers any treatment of, or prevention ofdisease in a vertebrate, a mammal, particularly a human, and includes:preventing the disease from occurring in a subject who may bepredisposed to the disease, but has not yet been diagnosed as having it;inhibiting the disease, ie., arresting its development; or relieving orameliorating the effects of the disease, ie., cause regression of theeffects of the disease.

The invention includes the use of various pharmaceutical compositionsuseful for ameliorating disease. The pharmaceutical compositionsaccording to one embodiment of the invention are prepared by bringing acompound of formula I, analogue, derivatives or salts thereof and one ormore pharmaceutically-active agents or combinations of compound offormula I and one or more pharmaceutically-active agents into a formsuitable for administration to a subject using carriers, excipients andadditives or auxiliaries.

Frequently used carriers or auxiliaries include magnesium carbonate,titanium dioxide, lactose, mannitol and other sugars, talc, milkprotein, gelatin, starch, vitamins, cellulose and its derivatives,animal and vegetable oils, polyethylene glycols and solvents, such assterile water, alcohols, glycerol and polyhydric alcohols. Intravenousvehicles include fluid and nutrient replenishers. Preservatives includeantimicrobial, anti-oxidants, chelating agents and inert gases. Otherpharmaceutically acceptable carriers include aqueous solutions,non-toxic excipients, including salts, preservatives, buffers and thelike, as described, for instance, in Remington's PharmaceuticalSciences, 20th ed. Williams & Wilkins (2000) and The British NationalFormulary 43rd ed. (British Medical Association and Royal PharmaceuticalSociety of Great Britain, 2002; http://bnf.rhn.net), the contents ofwhich are hereby incorporated by reference. The pH and exactconcentration of the various components of the pharmaceuticalcomposition are adjusted according to routine skills in the art. SeeGoodman and Gilman's The Pharmacological Basis for Therapeutics (7thed., 1985).

The pharmaceutical compositions are preferably prepared and administeredin dosage units. Solid dosage units include tablets, capsules andsuppositories. For treatment of a subject, depending on activity of thecompound, manner of administration, nature and severity of the disorder,age and body weight of the subject, different daily doses can be used.Under certain circumstances, however, higher or lower daily doses may beappropriate. The administration of the daily dose can be carried outboth by single administration in the form of an individual dose unit orelse several smaller dose units and also by multiple administration ofsubdivided doses at specific intervals.

The pharmaceutical compositions according to the invention may beadministered locally or systemically in a therapeutically effectivedose. Amounts effective for this use will, of course, depend on theseverity of the disease and the weight and general state of the subject.Typically, dosages used in vitro may provide useful guidance in theamounts useful for in situ administration of the pharmaceuticalcomposition, and animal models may be used to determine effectivedosages for treatment of the cytotoxic side effects. Variousconsiderations are described, eg. in Langer, Science, 249: 1527, (1990).Formulations for oral use may be in the form of hard gelatin capsules,in which the active ingredient is mixed with an inert solid diluent, forexample, calcium carbonate, calcium phosphate or kaolin. They may alsobe in the form of soft gelatin capsules, in which the active ingredientis mixed with water or an oil medium, such as peanut oil, liquidparaffin or olive oil.

Aqueous suspensions normally contain the active materials in admixturewith excipients suitable for the manufacture of aqueous suspensions.Such excipients may be suspending agents such as sodium carboxymethylcellulose, methyl cellulose, hydroxypropylmethylcellulose, sodiumalginate, polyvinylpyrrolidone, gum tragacanth and gum acacia;dispersing or wetting agents, which may be (a) a naturally occurringphosphatide such as lecithin; (b) a condensation product of an alkyleneoxide with a fatty acid, for example, polyoxyethylene stearate; (c) acondensation product of ethylene oxide with a long chain aliphaticalcohol, for example, heptadecaethylenoxycetanol; (d) a condensationproduct of ethylene oxide with a partial ester derived from a fatty acidand hexitol such as polyoxyethylene sorbitol monooleate, or (e) acondensation product of ethylene oxide with a partial ester derived fromfatty acids and hexitol anhydrides, for example polyoxyethylene sorbitanmonooleate.

The pharmaceutical compositions may be in the form of a sterileinjectable aqueous or oleaginous suspension. This suspension may beformulated according to known methods using suitable dispersing orwetting agents and suspending agents such as those mentioned above. Thesterile injectable preparation may also a sterile injectable solution orsuspension in a non-toxic parenterally-acceptable diluent or solvent,for example, as a solution in 1,3-butanediol. Among the acceptablevehicles and solvents which may be employed are water, Ringer'ssolution, and isotonic sodium chloride solution. In addition, sterile,fixed oils are conventionally employed as a solvent or suspendingmedium. For this purpose, any bland fixed oil may be employed, includingsynthetic mono-or diglycerides. In addition, fatty acids such as oleicacid may be used in the preparation of injectables.

Compounds of formula I may also be administered in the form of liposomedelivery systems, such as small unilamellar vesicles, large unilamellarvesicles, and multilamellar vesicles. Liposomes can be formed from avariety of phospholipids, such as cholesterol, stearylamine, orphosphatidylcholines.

Dosage levels of the compound of formula I of the present invention willusually be of the order of about 0.5 mg to about 20 mg per kilogram bodyweight, with a preferred dosage range between about 0.5 mg to about 10mg per kilogram body weight per day (from about 0.5 g to about 3 g perpatient per day). The amount of active ingredient which may be combinedwith the carrier materials to produce a single dosage will vary,depending upon the host to be treated and the particular mode ofadministration. For example, a formulation intended for oraladministration to humans may contain about 5 mg to 1 g of an activecompound with an appropriate and convenient amount of carrier material,which may vary from about 5 to 95 percent of the total composition.Dosage unit forms will generally contain between from about 5 mg to 500mg of active ingredient.

It will be understood, however, that the specific dose level for anyparticular patient will depend upon a variety of factors including theactivity of the specific compound employed, the age, body weight,general health, sex, diet, time of administration, route ofadministration, rate of excretion, drug combination and the severity ofthe particular disease undergoing therapy.

In addition, some of the compounds of the invention may form solvateswith water or common organic solvents. Such solvates are encompassedwithin the scope of the invention.

The compounds of the invention may additionally be combined with othertherapeutic compounds to provide an operative combination. It isintended to include any chemically compatible combination ofpharmaceutically-active agents, as long as the combination does noteliminate the activity of the compound of formula I of this invention.

In evaluation of the compounds of the invention, conventional measuresof efficacy may be used. For example, for asthma commonly-used primaryefficacy end-points include lung function tests such as spirometry ormeasurement of vital capacity, or self-monitoring using a peak flowmeter. For eczema, evaluation of efficacy may be based on:

-   (a) Physician's Static Assessment (PSA), a primary endpoint required    by the United States food and Drug Administration, which calls for    90% or greater improvement in signs and symptoms, is equivalent to a    clear or almost clear condition on at least two observations 21 days    apart, or-   (b) Physician's Global Assessment (PGA), which calls for 50% or    greater improvement.

The invention will now be described by way of reference only to thefollowing general methods and experimental examples.

General Methods

Cyclic peptide compounds of formula I are prepared according to methodsdescribed in detail in our earlier applications No. PCT/AU98/00490 andPCT/AU02/01427. An alternative method of synthesis is described in ourAustralian provisional application No. 2003902743. The entiredisclosures of these specifications are incorporated herein by thisreference. While the invention is specifically illustrated withreference to the compound AcF-[OPdChaWR] (PMX53), whose correspondinglinear peptide is Ac-Phe-Orn-Pro-dCha-Trp-Arg, it will be clearlyunderstood that the invention is not limited to this compound.

Compounds 1-6, 17, 20, 28, 30, 31, 36 and 44 disclosed in Internationalpatent application No. PCT/AU98/00490 and compounds 10-12, 14, 15, 25,33, 35, 40, 45, 48, 52, 58, 60, 66, and 68-70 disclosed for the firsttime in Australian provisional application No. PCT/AU02/01427 haveappreciable antagonist potency (IC50<1 μM) against the C5a receptor onhuman neutrophils. PMX53 (compound 17 of PCT/AU98/00490; also identifiedas compound 1 in PCT/AU02/01427) and compounds 33, 45 and 60 ofPCT/AU02/01427 are most preferred.

We have found that all of the compounds of formula I which have so farbeen tested have broadly similar pharmacological activities, althoughthe physicochemical properties, potency, and bioavailability of theindividual compounds vary somewhat, depending on the specificsubstituents.

The following general tests may be used for initial screening ofcandidate inhibitor of G protein-coupled receptors, and especially ofC5a receptors.

Receptor-Binding Assay

Assays were performed with fresh human PMNs, isolated as previouslydescribed (Sanderson et al, 1995), using a buffer of 50 MM HEPES, 1 mMCaCl₂, 5 mM MgCl₂, 0.5% bovine serum albumin, 0.1% bacitracin and 100 μMphenylmethylsulfonyl fluoride (PMSF). In assays performed at 4° C.,buffer, unlabelled human recombinant C5a (Sigma) or peptide,Hunter/Bolton labelled ¹²⁵I-C5a (˜20 pM) (New England Nuclear, Mass.)and PMNs (0.2×10⁶) were added sequentially to a Millipore Multiscreenassay plate (HV 0.45) having a final volume of 200 μL/well. Afterincubation for 60 min at 4° C., the samples were filtered and the platewashed once with buffer. Filters were dried, punched and counted in anLKB gamma counter. Non-specific binding was assessed by the inclusion of1 mM peptide or 100 nM C5a, which typically resulted in 10-15% totalbinding.

Data was analysed using non-linear regression and statistics withDunnett post-test.

Myeloperoxidase Release Assay for Antagonist Activity

Cells were isolated as previously described (Sanderson et al, 1995) andincubated with cytochalasin B (5 μg/mL, 15 min, 37° C.). Hank's BalancedSalt solution containing 0.15% gelatin and peptide was added on to a 96well plate (total volume 100 μL/well), followed by 25 μL cells(4×10⁶/mL). To assess the capacity of each peptide to antagonise C5a,cells were incubated for 5 min at 37° C. with each peptide, followed byaddition of C5a (100 nM) and further incubation for 5 min. Then 50 μL ofsodium phosphate (0.1M, pH 6.8) was added to each well, the plate wascooled to room temperature, and 25 μL of a fresh mixture of equalvolumes of dimethoxybenzidine (5.7 mg/mL) and H₂O₂ (0.51%) was added toeach well. The reaction was stopped at 10 min by addition of 2% sodiumazide. Absorbances were measured at 450 nm in a Bioscan 450 platereader, corrected for control values (no peptide), and analysed bynon-linear regression.

EXAMPLE 1 Reverse Passive Arthus Reaction in the Rat

A reverse passive peritoneal Arthus reaction was induced as previouslydescribed (Strachan et al., 2000), and a group of rats were pretreatedprior to peritoneal deposition of antibody with AcF-[OPdChaWR] (1) byoral gavage (10 mg kg⁻¹ dissolved in 10% ethanol/90% saline solution toa final volume of 200 μl) or an appropriate oral vehicle control 30 minprior to deposition of antibody. Female Wistar rats (150-250 g) wereanaesthetised with ketamine (80 mg kg⁻¹ i.p.) and xylazine (12 mg kg⁻¹i.p.).

The lateral surfaces of the rat were carefully shaved and 5 distinctsites on each lateral surface clearly delineated. A reverse passiveArthus reaction was induced in each dermal site by injecting Evans blue(15 mg kg⁻¹ i.v.), chicken ovalbumin (20 mg kg⁻¹ i.v.) into the femoralvein 10 min prior to the injection of antibody. Rabbit anti-chickenovalbumin (saline only, 100, 200, 300 or 400 μg antibody in a finalinjection volume of 30 μL) was injected in duplicate at two separatedermal sites on each lateral surface of the rat, giving a total of 10injection sites per rat. Rats were placed on a heating pad, andanaesthetic was maintained over a 4 h-treatment period with periodiccollection of blood samples. Blood was allowed to spontaneously clot onice, and serum samples were collected and stored at −20° C. Four hoursafter induction of the dermal Arthus reaction, the anaesthetised rat waseuthanased and a 10 mm² area of skin was collected from the site of eachArthus reaction. Skin samples were stored in 10% buffered formalin forat least 10 days before histological analysis using haematoxylin andeosin stain. Additionally, a second set of skin samples were placed in 1mL of formamide overnight, and the absorbance of Evans blue extractionmeasured at 650 nm, as an indicator of serum leakage into the dermis.FIG. 1 shows the optical density of dermal punch extracts followingintradermal injection of rabbit anti-chicken ovalbumin at 0-400 μgsite⁻¹ following pretreatment with AcF-[OPdChaWR] intravenously, orallyor topically. Data are shown as absorbance at 650nm as a percentage ofthe plasma absorbance, as mean values ±SEM (n=3-6). *indicates a P value≦0.05 when compared to Arthus control values.

Rats were pretreated with the C5aR antagonist, AcF-[OPdChaWR] (1) as theTFA salt, either intravenously (0.3-1 mg kg⁻¹ in 200 μL salinecontaining 10% ethanol, 10 min prior to initiation of dermal Arthus),orally (0.3-10 mg kg⁻¹ in 200 μL saline containing 10% ethanol by oralgavage, 30 min prior to initiation of dermal Arthus in rats denied foodaccess for the preceding 18 hours) or topically (200-400 μg site⁻¹ 10min prior to initiation of dermal Arthus reaction), or with theappropriate vehicle control. Topical application of the antagonistinvolved application of 20 μl of a 10-20 mg mL⁻¹ solution in 10%dimethyl sulphoxide (DMSO), which was then smeared directly onto theskin at each site, 10 min prior to induction of the Arthus reaction.

The saline-only injection site from rats treated with Evans blue onlyserved as antigen controls, the saline-only injection site from ratstreated with Evans blue plus topical DMSO only served as a vehiclecontrol, the saline-only injection site from rats treated with Evansblue plus either intravenous, oral or topical antagonist only served asantagonist controls, and Evans blue plus dermal rabbit anti-chickenovalbumin served as antibody controls. Topical application of thepeptide AcF-[OPGWR] which has similar chemical composition andsolubility as AcF-[OPdChaWR] (1), but with an IC₅₀ binding affinityof >1 mM in isolated human PMNs, served as an inactive peptide control.AcF-[OPGWR] was also dissolved in 10% DMSO and applied topically at 400μg site⁻¹ 10 min prior to initiation of the Arthus reaction.

TNFα Measurement

Serum TNFα concentrations were measured using an enzyme-linkedimmunosorbent assay (ELISA) kit (Strachan et al., 2000). Antibody pairsused were a rabbit anti-rat TNFα antibody coupled with a biotinylatedmurine anti-rat TNFα antibody. FIG. 2 shows the serum TNFαconcentrations at regular intervals after initiation of a dermal Arthusreaction, with group of rats pretreated with AcF-[OPdChaWR]intravenously, orally or topically. Data are shown as mean values ±SEM(n=3-6). *indicates a P value of ≦0.05 when compared to Arthus controlvalues.

Interleukin-6 Measurement

An ELISA method as described previously was used to measure serum andperitoneal lavage fluid interleukin-6 (IL-6) concentrations (Strachan etal., 2000).

Pathology Assessment

Rat skin samples were fixed in 10% buffered formalin for at least 10days, and stained with haematoxylin and eosin using standardhistological techniques. Dermal samples were analysed in a blind fashionfor evidence of pathology, and the degree of rat PMN infiltration wasscored on a scale of 0-4. Initiation of a dermal Arthus reactionresulted in an increase in interstitial neutrophils, which wasquantified in the following manner. Sections were given a score of 0 ifno abnormalities were detected. A score of 1 indicated the appearance ofincreased PMNs in blood vessels, but no migration of inflammatory cellsout of the lumen. A score of 2 and 3 indicated the appearance ofincreasing numbers of PMNs in the interstitial tissue and more prominentaccumulations of inflammatory cells around blood vessels. A maximalscore of 4 indicated severe pathological abnormalities were present indermal sections, with excessive infiltration of PMNs into the tissuesand migration of these cells away from blood vessels. FIG. 3 shows thatintradermal injection of increasing amounts of antibody leads to adose-responsive increase in the pathology index scored by dermal samples(A). Data are shown for dermal samples intradermally injected withsaline or 400 μg antibody per site (n=5) in rats pretreated withAcF-[OPdChaWR] intravenously (B) (n=3), orally (C) (n=3) and topically(D) (n=3). Data are shown as mean values ±SEM. * P≦0.05 when compared toArthus values using a non-parametric t-test.

EXAMPLE 2 Treatment of Asthma in a Tiger Cub

Respiratory problems were first noticed in Kaasha, a female Bengal Tigercub at the Dreamworld park, Australia, at the age of 10 weeks and around10 kg body weight. The initial clinical signs observed were a mild tomoderate increase in respiratory effort after feeding, followed within afew days by a continuous increase in respiratory effort. At no timeprior to the initial clinical signs had Kaasha's keepers noticed anychange in demeanour, appetite, activity level, or other parameter thatmight indicate illness. The rectal temperature was normal at the time ofinitial veterinary examination, and remained normal when measured overthe following weeks. The principal clinical signs included increasedrespiratory effort characterised by a prolonged two-phase forcedexpiration, fine pulmonary crackles particularly in dorsal lobes, and abronchointerstitial pattern and air entrapment on radiographs.

Initial treatment, pending definitive diagnosis, included antibiotics,Clavulox (7 mg/kg administered subcutaneously), doxycycline (5 mg/kgadministered orally), and enrofloxacin (5 mg/kg administeredsubcutaneously), and terbutaline (0.3 mg/kg administered orally).

Two weeks after initial detection of clinical signs, Kaasha experiencedan episode of severe dyspnoea with open-mouthed breathing. The episodelasted 20 to 30 seconds and resolved spontaneously.

Following repeated clinical examinations, radiography, clinicalpathology (blood: CBC, MBA) (Blood biochemistry and haematology) andbronchoalveolar lavage cytology, a diagnosis of lower airwayinflammation, of unknown aetiology, was made. Culture of bronchoalveolarlavage samples for microorganisms did not indicate the presence of anybacterial infection.

The anatomical diagnosis of neutrophil-dominated lower airwayinflammation was confirmed histologically by a thoracoscopically-guidedlung biopsy, although the pathologist also noted mixed inflammation ofthe interstitium. Further culture of the biopsy and polymerase chainreaction (PCR) for Feline viral rhinotracheitis virus and FelineCalicivirus and Chlamydia failed to provide convincing informationregarding the aetiology of the condition.

Approximately three weeks after initial clinical signs, the treatmentincluded Clavulox (7 mg/kg administered subcutaneously), doxycycline (5mg/kg administeredorally), and enrofloxacin (5 mg/kg administeredsubcutaneously) and terbutaline (0.3 mg/kg administered orally),nebulisation (saline) and percussion, use of Ventolin 100 μg by pufferinhalation and terbutaline (0.3 mg/kg administered orally) as necessaryto control dyspnoea. Prednisolone was given as a single daily dose of 2mg/kg, and Seretide (Salmeterol 50 μg plus fluticasone 250 μg) was givenusing a mask and spacer. Response to treatment was marked, withimprovement in respiratory effort and reduction in crackles audible onauscultation. This combination of treatment was maintained over the nextmonth.

During this month of therapy the following observations were made:

-   1. There was a radiographic improvement characterised by 35    reduction in the prominence of the bronchointerstitial pattern and    reduction in air entrapment.-   2. Throughout each day, and from day to day, there was a marked    variation in severity of respiratory clinical signs, although these    were not as severe as those observed in the initial stages of the    disease. Increase in respiratory effort was often observed when the    cub was taken into the airconditioned nursery, during exercise or    stress, and spontaneously, presumably in response to respiratory    irritants in the environment.-   3. Respiratory clinical signs responded rapidly to bronchodilators,    given either orally terbutaline (0.3 mg/kg orally) or by inhalation    (Ventolin puffer 100 μg).-   4. Although response to therapy was marked, there were never times    when the breathing pattern was normal.-   5. The cub developed a poor “staring” coat, poor muscling, retarded    growth rate, reduced activity level and playfulness, and relatively    poor appetite when compared with her littermate.

The clinical findings and response to various therapies were reviewed,and the diagnosis of feline asthma was made. This decision was basedupon the marked reactivity of the airways, marked and rapid response tobronchodilators, and general improvement of respiratory clinical signswith corticosteroid therapy.

Three months after onset of clinical signs, despite relativelyaggressive oral corticosteroid therapy Prednisolone 2 mg/kg once daily,the level of control of the disease was stable but not yet satisfactoryin terms of long-term health management. Consequently an experimentaltechnique involving direct injection of Prednisolone sodium succinate,1200 mg in a total volume of 30 ml (40 mg/ml aqueous solution), wasinstilled into the trachea under general anaesthesia. Recovery from theanaesthesia was uneventful, and within 24 hours there was a rapid andmarked improvement in respiratory effort.

Kaasha's keepers unanimously reported that the breathing patternimproved to virtually normal levels for one week, with no episodes ofdyspnoea during that period. However, the clinical pattern of labouredbreathing returned to pre-treatment levels at seven to nine days posttreatment. At this time therapy included oral corticosteroid at 2 mg/kg,use of inhaled Flixotide (Fluticasone 250 μg/dose) with and withoutSeretide (Salmeterol 50 μg plus fluticasone 250 μg/dose), use ofVentolin puffer, 100 μg, as necessary to control dyspnoea, andoccasional use of Pulmicort nebules (Budesonide 400 μg) by nebulisation.

It is important to note that use of inhaled medications in the cub wascharacterised by variability in the effectiveness of the daily dosegiven, as a result of variation in her compliance, keeper compliance,keeper competence, and daily frequency of administration.

Three weeks after the intra-airway steroid procedure, anotherexperimental therapy was applied. Injections of the C5a complementreceptor antagonist AcF-[OPdChaWR] (1) were administered at a dose rateof 0.3 mg/kg as single daily subcutaneous injections for six days,followed by twice-weekly injections for 8 weeks. At this time the doseof oral corticosteriod, Prednisolone approx 1 mg/kg reducing, had beenreduced to 20 mg per day because of concern regarding side effects ofprolonged high dose use. Kaasha's keepers were asked to pay particularattention to ensuring that inhaled medications were being applied in themost effective manner, to compensate for reduction in the oralcorticosteroid dose.

There was unanimous agreement among Kaasha's keepers that there was amoderate to marked improvement in breathing and in recovery time afterepisodes of dyspneoa following the week of daily AcF-[OPdChaWR] (1)injections. However, it was observed that the general breathing patternwas not as good during twice weekly treatments as it had been followingdaily injections, although recovery time was comparable.

The reduction in oral cortisone dosage and treatment with AcF-[OPdChaWR](1) corresponded with a marked improvement in the playfulness, generalactivity level, appetite and general demeanour of the tiger cub. Theaddition of a further medication, Singulaire, was not associated with anoticeable improvement in clinical signs.

As at July 2002 Kaasha was approximately 32 kg and 7 months of age, andwas being maintained on the following regimen:

-   Macrolone (prednisolone): 20 mg orally each evening; Singulaire    (montelukast sodium): 10 mg orally each evening;-   AcF-[OPdChaWR] (1): 3 mg/10 kg subcutaneously twice a week; Seretide    puffer (Salmeterol 50 μg plus fluticasone 250 μg/dose:) morning and    night, preceded by Ventolin, 100 μg, puffer;-   Flixotide puffer (Fluticasone): 250 μg/dose up to four times each    day; and-   Pulmicort nebulisation (Budesonide): 400 μg once a day as time    permits.

Further improvements in the therapeutic regime were tested with a viewto long-term control of the asthma. Measures were taken to improve theefficiency of puffer medication delivery in an attempt to reduce oreliminate the oral corticosteroid use. At this time Kaasha showed milddyspnoea at rest, and moderate to marked dyspnoea after exercise,exertion or stress, but this dyspnoea was not associated with visibledistress. Her behaviour, growth rate and appetite were only slightlyless than, or comparable with, her those of littermate.

A dietary trial was attempted, with complete replacement of the currentdiet by a different protein source, namely either lamb/mutton or rabbitexclusively.

Kaasha's condition deteriorated, and in early September 2002 she diedunder anaesthetic while undergoing a brain scan. From the pathologyreports it appears that the hyperoesinophilia was affecting other organsapart from the lung and the animal was becoming increasingly ill fromintestinal and renal effects. While it is not possible to draw anycausal connection, it is noted that in August 2002 treatment with PMX53had been discontinued. Post-mortem examination showed that the tiger cubhad hyperoesinophilia syndrome, which contributed to the asthma-likelung condition, and also caused lesions in the kidney and intestine.This condition also occurs in humans.

EXAMPLE 3 Allergic Dermatitis in a Dog

A kelpie dog was treated with PMX53 (1 mg/kg/day PO) for intermittentlameness, which was noticeable after prolonged exercise. Because of theintermittent nature of the lameness the owner, a veterinarian, found itdifficult to assess any improvement. However, the owner reported thatthe drug effected a marked improvement in the dog's allergic dermatitis,which had apparently resolved completely.

EXAMPLE 4 Treatment of Allergic Dermatitis in Dogs

Two dogs with dermatitis were treated with PMX53 (0.3 mg/kg in 30%polyethylene glycol 400: 70% 0.9% saline) as a subcutaneous injectiononce daily. Blood samples were collected after 4 weeks of treatment. Onedog was then treated with 0.6 mg/kg PMX53 subcutaneously for 4 daysbefore euthanasia and autopsy. Biochemistry and haematology was repeatedon the high-dose dog at this time. No abnormalities were detected in thelaboratory samples or on gross examination of the carcass. There was noevidence of irritation at the site of injection.

The second dog was bled for haematology and biochemistry after a totalof seven weeks treatment. No abnormalities were detected. This dog hadsevere allergic dermatitis, which was presumed to be due to fleaallergy; however, no antigen testing to confirm this was performed. Thedermatitis completely resolved following treatment with PMX53, as shownin FIG. 4. Both dogs were healthy for the duration of the experiment,with no signs of drug toxicity.

A very old dog (estimated age 13-16 years) admitted to a pound wasdiagnosed as having severe atopic dermatitis affecting 100% of the skinand the inside of the ear pinnae (otitis external, andkeratoconjunctivitis sicca (“dry eye”). The dog had broken skin over thedorsum of the tail, and both eyes were encrusted with yellow exudate.

Treatment of the skin condition with PMX53 was commenced using a topicalpreparation (5 mg/ml in 50% propylene glycol:50% water) applied to 25%of the body, including the tail, rump and right hind leg, once a day.The eyes were treated with PMX53 in an eye-drop formulation (5 mg/ml in30% polyethylene glycol:70% normal saline). The sores on the tailresolved within 3 days. The thickening of the skin over the stifle andespecially over the ischial tuberosity resolved noticeably, and the eyesimproved to the point of being essentially normal in appearance. The dogshowed no signs of itching.

The dog initially walked with a very stilted gait, but after treatmentwith PMX53 was able to walk and trot freely. This may either be due toan improvement in preexisting arthritis or to a less painful skin.

EXAMPLE 5 Treatment of Flea Allergy Dermatitis and Demodectic Dermatitisin Dogs

Demodex, also known as demodectic mange or red mange, is an infestationof the skin caused by the mite Demodex canis which causes dermatitis,skin thickening and hair loss, and is very common in dogs. Thiscondition is thought to be due partially to impaired immune responses inthe host. It is often associated with flea infestation, which itself cancause an allergic dermatitis. The skin irritation in infected animals issometimes very extensive, and results in loss of hairs and severe skinrashes.

Given the infectious nature of Demodex canis infestation,corticosteroids are not a suitable treatment because they suppress localimmune responses and worsen the condition by allowing the mites toproliferate.

(a) Two dogs suffering from demodectic dermatitis were treated for 13days with PMX53 (0.3 mg/kg in 30% polyethylene glycol 400:70% 0.9%saline) by subcutaneous injection. No discomfort was noted on injectingthis preparation. Both dogs showed a significant reduction in theinflammatory response in the skin, despite the fact that the challengeagent, fleas and demodex, had not been removed.

(b) A mastiff pup (approximately 6 months old) was diagnosed as havingdemodex infestation (folliculitis) of the head, involving both eyelids.This resulted in swelling of the lids, inversion of the lid margin andrubbing of hairs on the cornea (trichiasis). The eyes were red anddischarging, and the dog squinted because of the ocular pain.

The skin lesions on the top of the head were treated daily with topicalPMX53 daily (10 mg/ml in 30% polyethylene glycol: 70% 0.9% saline. Thiswas applied to the lesion so that the lesion was wet; the volume toachieve this was not recorded. After 5 days of treatment theinflammation in the skin was reduced, although the mites were stillpresent in scrapings taken from the lesion. This indicated that the drugcan moderate inflammation associated with this condition withoutactually killing the parasite.

The eyelids were treated once daily with PMX53 eye drops (10 mg/ml in30% polyethylene glycol:70% 0.9% saline. This was applied to the eyelidlesion so that the lesion was wet, and was also instilled into the eyes.Over 5 days the inflammation resolved to the point that the trichiasiswas relieved and the dog's eyes were comfortable and functional. Thiswas considered to be a very significant clinical response.

These results indicate that PMX53 may offer a means of controllinginflammation associated with the mite infestation without impairingimmune responses which are required to eliminate the parasite. Thisdemonstrates that PMX53 is a suitable anti-inflammatory agent to usewhere an infectious agent is present, and where common veterinarytreatments such as glucocorticoids would be contraindicated because oftheir suppression of local immune responses.

EXAMPLE 6 Treatment of Asthma in Cats

Asthma in humans has many causes, including allergens, physicalstimulants such as cold air or sulphur dioxide, and immune-basedaetiologies. Both cats and horses have a recognised clinical conditionwhich resembles human asthma. In horses with the condition known as“heaves”, asthma-like symptoms are caused by inhaled allergens,analogously to “allergic asthma”. In cats the cause of the airwayinflammation can be uncertain, but its clinical signs resemble thoseseen in humans, with bronchoconstriction causing difficult breathing.

Cats provide a preferred clinical model of human disease for testing ofthe C5a antagonist of the invention, because PMX53 has been shown tobind well to the feline C5a receptor. PMX53 binds less effectively tothe equine receptor, and the large size of horses means thatadministration of large quantities of drug is required. However, theequine model is not excluded.

Cats showing asthma-like respiratory pathology are selected from animalspresented to veterinary practices. The diagnosis is confirmed bystandard evaluation criteria, including routine blood biochemistry andhaematology, chest X-ray and bronchoalveolar lavage. Cats are treatedwith PMX53 orally at a dose of 1 mg/kg or subcutaneously at 0.3 mg/kg.Response to treatment is evaluated using clinical parameters, such aseasier breathing and reduction in peripheral blood eosinophilia. Arepeat of the bronchoalveolar lavage to confirm a reduction in airwayinflammation is also desirable.

Other animal model systems for asthma, in which asthma-like symptoms areprovoked by defined stimuli, are known in the art, and may also be usedin pre-clinical testing of the compounds of the invention. For example asheep model is described in PCT/AU02/00715. A number of reviews havebeen published; see for example Tobin, 2003; Isenberg-Feig et al, 2003;Bice et al, 2000; Drazen et al, 1999; andhttp://ajrccm.atsjournals.org/cgi/collection/asthma_airway_animalmodels.

Discussion

Cyclic peptides have several important advantages over acyclic peptidesas drug candidates (Fairlie et al 1995, Fairlie et al, 1998, Tyndall andFairlie, 2001). The cyclic compounds described in this specification arestable to proteolytic degradation for at least several hours at 37° C.in human blood or plasma, in human or rat gastric juices, or in thepresence of digestive enzymes such as pepsin, trypsin and chymotrypsin.In contrast, short linear peptides composed of L-amino acids are rapidlydegraded to their component amino acids within a few minutes under theseconditions. A second advantage lies in the constrained singleconformations adopted by the cyclic and non-peptidic molecules, incontrast to acyclic or linear peptides, which are flexible enough toadopt multiple structures in solution other than the one required forreceptor-binding. Thirdly, cyclic compounds such as those described inthis invention are usually more lipid-soluble and more pharmacologicallybioavailable as drugs than acyclic peptides, which can rarely beadministered orally. Fourthly, the plasma half-lives of cyclic moleculesare usually longer than those of peptides.

It will be apparent to the person skilled in the art that while theinvention has been described in some detail for the purposes of clarityand understanding, various modifications and alterations to theembodiments and methods described herein may be made without departingfrom the scope of the inventive concept disclosed in this specification.

References cited herein are listed on the following pages, and areincorporated herein by this reference.

REFERENCES

-   Bice D. E., Seagrave J, Green F. H. Inhal Toxicol. September    2000;12(9):829-62.-   Drazen et al, Clin Exp Allergy 1999; 29 Suppl 2:37-47.-   Fairlie, D. P., Wong, A. K.; West, M. W. Curr. Med. Chem., 1998, 5,    29-62.-   Fairlie, D. P., Abbenante, G., and March, D. Curr. Med. Chem., 1995    2 672-705.-   Gerard, C and Gerard, N. P. Ann. Rev. Immunol., 1994 12 775-808.-   Isenberg-Feig H., Justice, J. P., Keane-Myers, A. Current Allergy    and Asthma Reports 2003 3:70-78.-   Konteatis, Z. D., Siciliano, S. J., Van Riper, G., Molineaux, C. J.,    Pandya, S., Fischer, P., Rosen, H., Mumford, R. A., and    Springer, M. S. J. Immunol., 1994 153 4200-4204.-   Sanderson, S. D., Kirnarsky, L., Sherman, S. A., Vogen, S. M.,    Prakesh, O., Ember, J. A., Finch, A. M. and Taylor, S. M. J. Med.    Chem., 1995 38 3669-3675.-   Strachan, A. J., Haaima, G., Fairlie, D. P. and Taylor, S. M. J    Immunol. 164: 6560-6565, 2000.-   Tobin M. J. Am. J. Respir. Crit. Care Med. 167 (3): 319-   Tyndall, J. D. A. and Fairlie, D. P. Curr. Med. Chem. 2001, 8,    893-907.

1. A method of treatment of a hypersensitivity condition, comprising thestep of administering an effective amount of an inhibitor of a Gprotein-coupled receptor to a subject in need of such treatment in whichthe inhibitor is a compound which (a) is an antagonist of a Gprotein-coupled receptor, (b) has substantially no agonist activity, and(c) is a cyclic peptide or peptidomimetic compound of formula I

where A is H, alkyl, aryl, NH₂, NH-alkyl, N(alkyl)₂, NH-aryl, NH-acyl,NH-benzoyl, NHSO₃, NHSO₂-alkyl, NHSO₂-aryl, OH, O-alkyl, or O-aryl; B isan alkyl, aryl, phenyl, benzyl, naphthyl or indole group, or the sidechain of a D- or L-amino acid, but is not the side chain of glycine,D-phenylalanine, L-homophenylalanine, L-tryptophan, L-homotryptophan,L-tyrosine, or L-homotyrosine; C is the side chain of a D-, L- orhomo-amino acid, but is not the side chain of isoleucine, phenylalanine,or cyclohexylalanine; D is the side chain of a neutral D-amino acid, butis not the side chain of glycine or D-alanine, a bulky planar sidechain, or a bulky charged side chain; E is a bulky substituent, but isnot the side chain of D-tryptophan, L-N-methyltryptophan,L-homophenylalanine, L-2-naphthyl L-etrahydroisoquinoline,L-cyclohexylalanine, D-leucine, L-fluorenylalanine, or L-histidine; F isthe side chain of L-arginine, L-homoarginine, L-citrulline, orL-canavanine, or a bioisostere thereof; and X is —(CH₂)_(n)NNH— or(CH₂)_(n)—S—, where n is an integer of from 1 to 4; —(CH₂)₂O—;—(CH₂)₃O—; —(CH₂)₃—; —(CH₂)₄—; —CH₂COCHRNH—; or —CH₂—CHCOCHRNH—, where Ris the side chain of any common or uncommon amino acid.
 2. A methodaccording to claim 1, in which n is 2 or
 3. 3. A method according toclaim 1, in which A is an acetamide group, an aminomethyl group, or asubstituted or unsubstituted sulphonamide group.
 4. A method accordingto claim 2, in which A is a substituted sulphonamide, and thesubstituent is an alkyl chain of 1 to 6 carbon atoms, or a phenyl ortoluyl group.
 5. A method according to claim 4, in which the substituentis an alkyl chain of 1 to 4 carbon atoms.
 6. A method according to claim1, in which B is the side chain of L-phenylalanine or L-phenylglycine.7. A method according to claim 1, in which C is the side chain ofglycine, alanine, leucine, valine, proline, hydroxyproline, orthioproline.
 8. A method according to claim 1, in which D is the sidechain of D-Leucine, D-homoleucine, D-cyclohexylalanine,D-homocyclohexylalanine, D-valine, D-norleucine, D-homo-norleucine,D-phenylalanine, D-tetrahydroisoquinoline, D-glutamine, D-glutamate, orD-tyrosine.
 9. A method according to claim 1, in which E is the sidechain of an amino acid selected from the group consisting ofL-phenylalanine, L-tryptophan and L-homotryptophan, or is L-1-napthyl orL-3-benzothienyl alanine.
 10. A method according to claim 1, in whichthe inhibitor is a compound which has antagonist activity against C5aR,and has no C5a agonist activity.
 11. A method according to claim 1, inwhich the inhibitor has potent antagonist activity at sub-micromolarconcentrations.
 12. A method according to claim 1, in which the compoundhas a receptor affinity IC50<25 μM, and an antagonist potency IC50<1 μM.13. A method according to claim 1, in which the compound is selectedfrom the group consisting of compounds 1 to 6, 10 to 15, 17, 19, 20, 22,25, 26, 28, 30, 31, 33 to 37, 39 to 45, 47 to 50, 52 to 58 and 60 to 70described in PCT/AU02/01427.
 14. A method according to claim 13, inwhich the compound is PMX53 (compound 1), compound 33, compound 60 orcompound 45 described in PCT/AU02/01427.
 15. A method according to claim1, in which the inhibitor is used in conjunction with one or more otheragents for the treatment of hypersensitivity conditions.
 16. A methodaccording to claim 15, in which the other agent is infliximab or is aninhibitor of C3a.
 17. A method according to claim 1, in which thetreatment is to prevent or alleviate acute recurrences of ahypersensitivity condition.
 18. A method according to claim 1, in whichthe treatment is to prevent or alleviate a primary occurrence of ahypersensitivity condition.
 19. A method according to claim 1, in whichthe hypersensitivity condition is selected from the group consisting ofType II immediate hypersensitivity (cytotoxic) and Type III(complex-mediated) immediate hypersensitivity, asthma, eczema,dermatitis, Arthus-type reactions, glomerulonephritis, hypereosinophiliasyndrome, and farmer's lung.
 20. A method according to claim 19, inwhich the hypersensitivity condition is eczema or dermatitis.
 21. Amethod according to claim 20, in which the hypersensitivity condition isdemodectic mange or flea allergy.
 22. A method according to claim 20, inwhich the inhibitor is administered orally or topically.
 23. A methodaccording to claim 19, in which the hypersensitivity condition isasthma.
 24. A method according to claim 22, in which the inhibitor isadministered orally, intranasally or by inhalation.
 25. A methodaccording to claim 1, in which the inhibitor is used in conjunction withone or more other agents for the treatment of hypersensitivityconditions.